The broad objective of this proposal is to identify a disease gene responsible for North Carolina macular dystrophy and to elucidate the underlying molecular mechanisms that lead to macular degeneration. North Carolina macular dystrophy (OMIM #136550) is an autosomal dominant, highly penetrant macular degeneration characterized by variable phenotypes including confluent drusen in the macula, macular atrophy, and choroidal neovascularization. Three specific aims are designed to test the underlying central hypothesis: that the protein product of the gene for North Carolina macular dystrophy, designated as MCDR1, is essential for the normal function of the macula and that the macular degeneration phenotype is associated with mutations in the MCDR1 gene. The three specific aims are: 1) to identify the disease gene for North Carolina Macular Dystrophy, MCDR1; 2) to characterize the mRNA and protein expression profiles and function of MCDR1; 3) to study the biological effect of MCDR1 in a mouse system. It is important to study the genetic basis of North Carolina macular dystrophy, as it causes juvenile macular degeneration with visual loss. Furthermore, North Carolina macular dystrophy shares important clinical features with age-related macular degeneration (AMD). Drusen is a hallmark of AMD and choroidal neovascularization (CNV) is one of the most important complications of AMD. Both of them are present in patients with North Carolina macular dystrophy. Therefore, these observations make North Carolina macular dystrophy a unique genetic model for AMD. Understanding the molecular mechanisms of MCDR1 should lead to novel insights into the pathogenesis of macular degeneration. Elucidation of the function of the MCDR1 gene may increase our understanding of retinal cell biology in general and drusen formation in particular. Finally, this study may provide information for pursuing novel strategies for treatment of macular degeneration.